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Re: [Amps] Old Moto RF Decks

To: <>
Subject: Re: [Amps] Old Moto RF Decks
From: "Peter Voelpel" <>
Date: Thu, 4 Dec 2014 01:33:59 +0100
List-post: <">>
The Tram family of broadcast AM/DRM transmitters by Transradio seem to have
no IMD issues. They make use of adaptive pre distortion and use LDMOS,
however not sure whether Freescale ore NPX hardware but I could find out.
A 10KW unit has just been taken out of business and is on sale by a
broadcast technician responsible for that site before.


-----Original Message-----
From: Amps [] On Behalf Of Carl
Sent: Dienstag, 2. Dezember 2014 01:02
To: John Kinney;
Subject: Re: [Amps] Old Moto RF Decks

BUT, harmonics and IMD are two completely different animals.

Now when is Freescale going to offer a 2-30 or 2-50 mHz device that has high

efficiency and very low IMD at the same time and be targeted at the linear 
SSB amp market?


----- Original Message ----- 
From: "John Kinney" <>
To: "Carl" <>; <>
Sent: Monday, December 01, 2014 6:17 PM
Subject: RE: [Amps] Old Moto RF Decks

Hi Carl,

You are correct.  I saw very poor IMDs on the two tube version at anything 
over about 400 Watts.  I friend of mine helped me build a filter, 5 poles as

I recall, for use on the output.  It brought the 2nd and 3rd harmonics down 
quite nicely, using two tone 1 kHz spacing.  We used an Anritsu Spectrum 
Analyzer for monitoring into a 2KW dummy load and the 2nd and 3rd harmonics 
were down about 50 and 70 db as I recall.

It was a lot of fun playing with those old amps.


John Kinney
RF Solutions Team
Freescale Semiconductor
Tempe, Arizona
(480) 413-4290

-----Original Message-----
From: Carl []
Sent: Monday, December 01, 2014 1:43 PM
To: Kinney John-R17512;
Subject: Re: [Amps] Old Moto RF Decks

SSB IMD goes up rapidly above 300W per tube even with simplistic screen 
regulation. Be a good neighbor on the bands with those rather aged and 
obsolete designs (1947) that predate widespread SSB use.

Collins rated their 1960 AN/URC-32 at 500W with a pair of lower IMD 
4CX250R's at 2000V while Eimac rated them to 2500V with poor IMD specs.
Those transceivers, at 6' tall, ran fine without clobbering other close 
channel USN users.


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